Scroll machinery for fluid compression or expansion is typically comprised of two upstanding interfitting involute spiroidal wraps or scrolls which are generated about respective axes. Each respective scroll is mounted upon an end plate and has a tip disposed in contact or near contact with the end plate of the other respective scroll. Each scroll further has flank surfaces which adjoin, in moving line contact or near contact, the flank surfaces of the other respective scroll to form a plurality of moving chambers. Depending upon the relative orbital motion of the scrolls, the chambers move from the radially exterior ends of the scrolls to the radially interior ends of the scrolls for fluid compression, or from the radially interior ends of the scrolls to the radially exterior ends of the scrolls for fluid expansion. The scrolls, to accomplish the formation of the chambers, are put in relative orbital motion by a drive mechanism. Either one of the scrolls may orbit or both may rotate eccentrically with respect to one another.
A typical scroll machine, according to the design which has a non-orbiting scroll, includes an orbiting scroll which meshes with the non-orbiting scroll, a thrust bearing to take the axial loads on the orbiting scroll, and a lubricant supply system for lubricating the various moving components of the machine including the thrust bearing. Accordingly, there is a continuous need in the field of scroll machines tier improved lubricating techniques throughout the operating range of the machinery.
Conventionally, in low-side scroll compressors, a portion of the lubrication is suction gas flow which is allowed to pick up the overspray of lubricant oil from the compressor's components and circulate it throughout the compressor. Suction gas is baffled and routed through the compressor in such a way as to control the amount of oil which is picked up by the suction gas to a tolerable level for compressor operation at rated operating conditions. At the hotter "high compression ratio" conditions, where it may be desirable to have a higher oil circulation rate for its cooling effect, the oil circulation rate is actually lower. This lower oil circulation rate is the result of the suction gas being much less dense at the higher compression ratios and therefore the suction gas does not entrain as much of the oil overspray.
Accordingly, it would be desirable to control the amount of oil which is entrained by the suction gas throughout the operating range of the compressor. This would include the hot conditions which occur if high compression ratios are experienced and also the lower temperature operating ranges of the compressor. In addition, it would be desirable to provide some form of mist lubrication to prevent scroll tip galling.
It is therefore a primary objective of this invention to provide an improved lubrication system which utilizes the centrifugal forces generated by a rotating upper counter-balance weight to influence the flow of lubricating fluid in a portion of the lubrication system. The lubrication system of the present invention can provide a constant oil circulation rate over the entire operating envelope of the compressor or the present invention can be adapted to provide a nominal oil circulation rate at cooler oil temperatures and a selectively higher oil circulation rate at higher oil temperatures if desired.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.